The glass cleaning robot also referred to as “Winbot” is a common small household electrical appliance. Generally, while operating normally, the existing Winbot is supplied with power by an external power supply. In addition, the Winbot is provided with a built-in battery which may be a dry battery or a rechargeable battery. The external power supply can recharge the built-in battery while supplying power to the Winbot. When the external power supply suddenly suffers outage due to unforeseen events, the glass cleaning robot is automatically switched to a built-in battery power-on mode. However, if the Winbot locates at a relatively high position on the surface of a glass, it will hamper the user to take down the Winbot and also can easily lead to danger. Furthermore, the higher the position from which the Winbot falls, the more easily the Winbot is damaged or the more seriously pedestrians are hurt.